Figure 3
GS misexpression with class-specific Gal4 drivers in larval da neurons. (a) Control class I da neuron ddaE visualized with GAL4221 driving UAS-mCD8::GFP. (b) Misexpression of GSd458 caused increased numbers of small dendritic branches, though the primary branches were unaffected. (c) C161-GAL4 drives expression in classes I-III, but not class IV, allowing better visualization of spine-like protrusions on the class III neuron ddaA. Arrowheads in (c,d) mark the cell body of ddaA. (c') Tracing of ddaA cell body and dendrites in (c). (d) Misexpression of GSd236: primary dendrites of ddaA are devoid of spine-like protrusions. (d') Tracing of ddaA cell body and dendrites in (d). (e) ppk1.9-GAL4 is a class IV da neuron driver, revealing the complex dendritic tree of ddaC. (f) Misexpression of Gsd454: reductions in the number and growth of higher order branches of ddaC. (g) Quantification of branch ends per neuron for the genotypes shown in (a-f), showing class specificity of branching defects. In class I ddaE neurons (left), GSd458 increases branching dramatically (asterisk denotes t-test, P < 1e-5), while GSd454 has no effect. In class IV ddaC neurons (right), both GSd458 and GSd454 reduce branching relative to controls (wild type (WT); asterisks denote t-tests, both P < 1e-8). In both cases, the total length of the dendritic arbor was dramatically reduced (control (WT) = 17,389 ± 422 μm versus GSd454 = 8,544 ± 657 μm (t-test P < 1e-10) or versus GSd458 = 2,650 ± 296 μm (t-test, P < 1e-16). Since higher order branches were reduced but the growth of primary dendrites was mostly unaffected, there was no effect on dendritic field area (for example, control = 304,899 ± 7,115 μm2 versus GSd454 = 301,475 ± 9,141 μm2; t-test P > 0.8). In class III ddaA neurons (middle), GSd236 dramatically reduced the number of short spine-like protrusions (t-test, P < 0.003), but had no effect on the total length of primary dendrites (control = 1,736 ± 137 μm versus GSd236 = 2,132 ± 157 μm; t-test P > 0.1). All images are maximal Z-projections of stacked confocal images. Anterior is left and ventral is down. Scale bars: (a-d) = 50 μm; (e,f) = 100 μm.